It is necessary because if you don't have a confirmed opinion with textual evidence to back it up you wont have a good argument.
Answer:
I am not sure but, its not California or Mexico so its either got to be Northern Mexico or Coastal Mexico
Explanation:
After Hades steals Persephone, she eats a pomegranite and thus cant return to Olympus or the mortal world. Hades and Demeter (Persephone's mom) compromise and she only has to stay in the underworld for 1/3 of the year.
I believe it is either A or B but I really think it is B.
Hope This Helps.